Harvey Kneeslapper appeared on Sesame Street as a mad practical joker, always pulling pranks on others. Usually, his pranks involved either letters or numbers, which he would slap onto his victims (who were often made from Fat BlueAnything Muppets; one of these was a look-alike, and sound-alike, for Mr. Johnson). In most of his skits, his pranks succeeded, much to the annoyance of his dupes. However, on rare occasions, Harvey's pranks backfired on him, such as the time he filled up an entire closet and waited for somebody to open the door. Such instances usually occurred in skits where he explained his prank to the audience.

He once appeared in a Sesame Street News Flash sketch, where he made a prank call about somebody standing out in a snowstorm.

Eventually, his raucous laugh became too hard on Frank Oz's throat, and Harvey, who was always considered a one-joke character, was dropped from the show.[1] Even after Harvey stopped appearing in new segments, his existing segments continued to be used in new episodes up until Season 32.

Harvey sets up a bucket of confetti above a door, so that whoever pulls the rope attached to the bucket will get the confetti dumped on them. Instead, a little girl walks by and pulls the rope, so that the confetti lands on Harvey!Two variations of this sketch were made.

Part 1: Harvey hangs an "OPEN" sign on a closet and has filled it with so many toys that when somebody opens it, all of the toys in the closet will fall on that person. A girl opens the closet, but none of the toys fall out. When Harvey opens it after she leaves, they fall all over him.

Part 2: Harvey has refilled the closet. A boy tries to open it, but the door is stuck. When the boy has left, Harvey opens the closet, and the toys land on him again.Part 3: Harvey has refilled the closet again. The boy and girl come by again and open the door. Instead of toys falling, the closet leads to another place. After the two of them have gone through and closed the door behind them, Harvey opens the closet, and the toys fall on him.
Online: Sesamestreet.org part 1: (sesamestreet.org) part 2: (sesamestreet.org) part 3: (sesamestreet.org)

Harvey goes to a man and asks, "Do you mind if I take a picture of you?" The man gives him permission, but Harvey asks, "What's down there?" When the man looks down, Harvey slaps the letter U on top of the man's head, takes a picture of it, and says "Thank U!" before he leaves.

Ernie, performing as Robin Hood, is interviewing some potential new "merry men". After the first two applicants turn out to be sad and angry, respectively, Ernie hires the third (Harvey) on the spot because he seems suitably merry... only to fire him just as quickly after he goes overboard rattling off one-liner jokes.

Part 1: Kermit has received a phone call which tells him that there is someone who has been standing out in a terrible snow storm for a long time. Kermit asks everyone who passes by if they are that person, but everyone he asks has only been out in the snow for a short time. Kermit refuses to give up, however, and tells us to stay tuned.

Part 2: Kermit, now shivering a little, is still looking for the person who's been standing out in the snow for a long time. He even asks Farley, who has been out for only a short time. Still no success yet.
Part 3: Kermit is now buried up to his neck in snow, colder than ever. He calls the attention of passerby Harvey Kneeslapper, who tells Kermit that he is the one who made the call, which was a prank call. As it turns out, Kermit was the one standing out in the storm.
Video: The Best of Kermit on Sesame Street (1998, clip of part 3 only)

Harvey explains to the audience that he is holding a joy buzzer in his hand and plans on asking somebody to give him five, shocking his victim's hand. However, when he asks a victim to "Gimme five!", the other man slaps a number 5 on him.

Harvey tells the Fat Blue mailman that he has a letter for his mother: the letter R! (Note: A similar practical joke was pulled in The Muppet Show episode 115, which also included the letter R and was pulled by another Frank Oz character, Fozzie Bear.)

Away From

In his first appearance, salesman Harvey asks Tony if he gets attacked by monsters and run over by crowds. Herry Monster attacks him and a crowd walks all over him, so the answer is yes. Harvey has a simple solution for Tony: AWAY FROM! The next time those things happen to Tony, he can get AWAY FROM them.

Sticky Four

Harvey Kneeslapper tells a man that "stickys" are really useful. The man asks, "What's a sticky for?". Then Harvey slaps a number 4 on the man's chest and says, "This is sticky, and it's a four!".